The present invention relates to an apparatus for fixing in position substrates that each have an inner hole, and includes a housing and an element disposed in the housing and introducible into the inner hole.
Such an apparatus can be used, for example, at various stations of an apparatus for the adhesive joining of substrates, as is described, for example, in DE-A-197 18 471, which is not prepublished and which belongs to the Applicant of the present application. In particular, the inventive apparatus is suitable for use with an apparatus for drying substrates, as described in the not prepublished DE-197 21 689, which belongs to the Applicant of the present application. To avoid repetition, the content of the aforementioned applications are incorporated for their content into this application. With the above apparatus, substrates are respectively deposited on a support for specific treatment steps in order, for example, to carry out an adhesive joining of two substrates or a drying of substrates. In this connection, the support surfaces provide no fixing of the substrates that are to be treated and positioned, so that the substrates can slide, especially two substrates that are to be adhesively joined can slide. This in turn affects the treatment process, which can lead to deterioration in the quality of substrates being treated.
DE-A-196 44 158 discloses an apparatus for grasping objects having a through opening. The apparatus has a gripper 12 that comprises a base body 4, a push member 9 that is axially moveable in the base body 4, and balls 6 that are disposed in the base body 4 and that, by means of an axial movement of the push member within the main body, can be shifted outwardly beyond the outer periphery of the main body 4.
DE-A-196 18 278 discloses a clamping device for drawing in and clamping a tool holder having a hollow cone shaft in the tool receiving means of a main spindle. With this device, clamping jaws for the securement of the tool holder are spread apart by means of a clamping mechanism that is displaceable relative to the clamping jaws.
From the publication xe2x80x9co+p-xc3x6lhydraulik und pneumatik-22 (1978) Nr. 1, page 10, there is known an inner hole gripper that fixes a substrate in position by means of a pneumatic expansion of an element that is introduced into an inner hole of the substrate.
DE-A-195 29 537 furthermore discloses an apparatus pursuant to the introductory portion of claim 1 .
It is therefore an object of the present invention to provide an apparatus of the aforementioned type for fixing in position substrates that are each provided with an inner hole, whereby the apparatus, with straightforward technical means and simple handling of the apparatus, enables a good fixing of the substrates in position in order to enable lower rejection rates and a better quality of the finished substrates.
The stated object is inventively realized in that the element that is introducible into the inner hole includes an outer element that is axially moveable relative to the housing, and an inner element that is axially moveable relative to the housing, whereby the outer element can be expanded or spread apart by means of a relative movement of the elements. Due to the expansion of the outer element in the inner hole of a substrate, the substrate is on the one hand fixed in position and is centered relative to the outer element. In particular, with substrates that are to be adhesively interconnected and are yet to be dried, there also results in this connection a good centering of the two substrates relative to one another. Due to the fact that not only the inner element, but also the outer element, are axially moveable relative to the housing, there results a simple possibility for introducing and removing these elements into and out of an inner hole of a substrate.
The outer and/or inner element is advantageously cylindrical in order to achieve a straightforward configuration and to be able to reliably come into engagement with the inner hole of the substrate or substrates.
In order to provide the expandability of the outer element in a simple manner, slots are provided in an end region of the outer element. The outer element is advantageously elastically expandable, i.e. after the expansion the outer element elastically returns to the non-expanded state and thus releases the engagement with the substrate or substrates.
Pursuant to one specific embodiment of the invention, the outer element is provided in the region of the slots with a tapering inner diameter by means of which the ability to expand is achieved during a relative movement of the elements.
The outer element can advantageously be axially biased by means of a biasing device so that it is biased in a particular axial position in which the outer element is disposed in an inner hole of a substrate. A particularly suitable biasing device is a spring.
Pursuant to one preferred specific embodiment, the inner element has an inclined surface on the outer periphery that is advantageously complementary to the tapering inner diameter of the outer element in order to expand the outer element in a manner that is as free from resistance as possible during a relative movement of the elements.
By means of a biasing device, the inner element can advantageously be axially biased into a position that expands the outer element in order to bring the inner element in a simple manner into a position in which the inner element expands the outer element. For this purpose, the biasing device is advantageously a spring.
To ensure that at a pressure that is exerted upon the apparatus from the outside prior to a movement of the outer element initially the expansion of the outer element is terminated, the biasing device for the inner element has a smaller spring constant than does the biasing device for the outer element.
The outer element preferably has a support surface for the biasing device for the outer and inner elements.
Pursuant to a further specific embodiment of the invention, the outer and inner elements can be axially biased by a common biasing device, which is advantageously a spring. By utilizing a common biasing device, the number of components that form the apparatus can be reduced.
In order to limit the relative movement of the elements relative to one another, and to prevent the elements from coming apart, the outer element, in a non-expandable end region, is provided with a shoulder in the inner periphery.
The inner element advantageously has a projection that can extend out of the outer element in order in a simple manner, by pressure upon the projection, to enable a relative movement between the elements.
Pursuant to a further preferred specific embodiment of the invention, the housing that receives the moveable outer and inner elements is stationary in order to form a fixed receiving device.
In order to provide a better hold for the fixed substrate or substrates, the housing advantageously has a substrate support surface.
At one end the housing advantageously has a base wall in order to form a counter surface for the biasing device that biases the outer and/or inner element.
The specification incorporates by reference the disclosure of German priority document 198 18 478.6 of Apr. 24, 1998 and International priority document PCT/DE99/02500 of Apr. 24, 1999.